Field of the Invention
The present invention relates to a semiconductor device and a method of manufacturing a semiconductor device.
Background Art
Heretofore, a semiconductor device including a multilayer electrode film provided on a silicon substrate has been known. Such semiconductor devices are disclosed in, for example, Japanese Patent Laid-Open Nos. 2013-194291 and 2010-129585. For example, a structure illustrated in FIG. 6 of Japanese Patent Laid-Open No. 2013-194291 includes barrier metal such as Ti, an Al alloy electrode made of AlSi alloy or the like, a Ni electrode, and an Au electrode, which are stacked on a surface of a silicon substrate.
A Si—Ti junction formed by providing an electrode made of titanium (Ti) on an N-type silicon (Si) has favorable ohmic contact properties. To obtain a strong Si—Ti junction, ideally, it is preferable to carry out a high-temperature process at approximately 700° C. to obtain a reaction layer of titanium silicide or the like. However, such a high-temperature process has the problem that functions of an element structure portion, an electrode film, and a protective film already formed on a semiconductor substrate are deteriorated. One conceivable way to cope with this problem is to avoid carrying out such a high-temperature process and use a Si—Ti junction without a reaction layer of titanium silicide or the like. However, in that case, there is a problem that a heat treatment process, which is 200 degrees Celsius or higher, performed on a multilayer electrode film formed by overlaying another electrode film on the titanium electrode causes Si—Ti interface delamination due to stress in the multilayer electrode film.